• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.1
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• pp.166-172
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• 2001

A RF wideband receiver for INMARSAT-B satellite communications system was composed of low noise amplifier and high gain amplifier, The low noise amplifier used to the resistive decoupling circuit for input impedance matching and self-bias circuits for low noise. The high gain amplifier consists of matched amplifier type to improve receiver gain. The active bias circuit can be used to provide temperature stability without requiring the large voltage drop or relatively high-dissipated power needed with a bias stabilization resistor. The bandpass filter was used to reduce a spurious level. As a result, the characteristics of the receiver implemented here show more than 60 dB in gain and less than 1.8:1 in input and output voltage standing wave ratio(VSWR), especially the carrier to noise ratio which is input signal level -126.7 dB m at 1537.5 MHz is a 45.23 dB /Hz at a 1.02 kHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.1
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• pp.90-98
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• 1999

This paper presents a wideband single-balanced mixer using a diode which can be used in RF receiver of microwave measurement systems. For wideband characteristic, local oscillator(LO) signal is provided to diode with low loss using a coplanar waveguide-to-slotline balun. For high isolation characteristic radio frequency (RF) port and intermediate frequency (IF) port are designed using directional coupler. This mixer presents 30.5~31.17dB conversion loss whose flatness is within 1dB for 9 kHz~2.6 GHz wideband RF signal, and above 30 dB isolation for LO signal.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.1
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• pp.61-72
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• 1997

The implementation of base station transceiver for Wideband CDMA(Code Division Multiple Access) PCS(Personal Communication Service) system using spread spectrum CDMA technology is presented in this paper. The receiver that requires wide dynamic range and high sensitivity and the transmitter that has good spurious emission supression were designed and implemented with 5 MHz RF channel bandwidth. This paper shows the some factors that should be considered and simulated using the RF simulation S/W with commercial and customized components. The implemented transceiver based on the simulation gave good results that satisfied the functional specifications of the transceiver.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.12
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• pp.1193-1200
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• 2016

In this paper, we developed a system for measuring a passive intermodulation distortion signal of the mobile communication RF module having a wide band characteristic. The Broadband was designed to represent the characteristics of the receiver to meet the low noise characteristics and wideband characteristics in the RF receiver were to represent a wide dynamic range(high dynamic range)from the RF receiving end. PIMD designed passive intermodulation distortion signal measured by applying the FPGA / DSP in the system was measured to record the program on the PC. Variable up to 650MHz-2700MHz showed up to-138dBc measured PIMD3.

• Journal of Communications and Networks
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• v.14 no.5
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• pp.501-509
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• 2012

This paper proposes a joint timing synchronization, channel estimation, and data detection for the impulse radio ultra-wideband systems. The proposed timing synchronizer consists of coarse and fine timing estimation. The synchronizer discovers synchronization points in two stages and performs adaptive threshold based on the maximum pulse averaging and maximum (MAX-PA) method for more precise synchronization. Then, iterative channel estimation is performed based on the discovered synchronization points, and data are detected using the selective rake (S-RAKE) detector employing maximal ratio combining. The proposed synchronizer produces two signals-the start signal for channel estimation and the start signal for start frame delimiter (SFD) detection that detects the packet synchronization signal. With the proposed synchronization, channel estimation, and SFD detection, an S-RAKE receiver with binary pulse position modulation binary phase-shift keying modulation was constructed. In addition, an IEEE 802.15.4a channel model was used for performance comparison. The comparison results show that the constructed receiver yields high performance close to perfect synchronization.

• Journal of Advanced Navigation Technology
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• v.11 no.3
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• pp.274-280
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• 2007

An ultra-wideband signal is characterized by a radiated spectrum with wide bandwidth around a relatively low center frequency. In this paper, the bit error rate (BER), packet error rate (PER), and data throughput performance for an ultra-wideband system with M-ary correlation receiver are analyze in additive white Gaussian noise (AWGN) and co-channel interference channel. To evaluate the performance of UWB system, a set of UWB communication waveform as pulse position modulated (PPM) signals consisting of more than one UWB pulse is used. The M-ary PPM signals are defined to be equally correlated in order to simplify the system performance analysis. The analysis for system performance shows that the wireless channel error significantly degrades throughput performance and can be effectively increased by hybrid ARQ scheme. Also, an attempt for comparing the data throughput of ultra-wideband system on different performance improvement schemes and parameters has been made. From the performance evaluation process, it is shown that the effects of wireless channel and hybrid ARQ scheme for ultra wideband M-ary PPM system can be evaluated by means of a suitable combination of the PER, throughput vs. signal-to-noise power ratio per bit.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.4
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• pp.1-8
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• 2011

In this paper, a microstrip bandpass filter(BPF) with 3 dB bandwidth of more than 50 % at center frequency of 30 GHz was implemented. The implemented BPF is to be used as ASK(Amplitude Shift Keying) transmission and reception filters in IF band for THz transmitter and receiver capable of 10 Gb/s wireless data transmission. The microstrip BPF with ultra-wideband characteristics was implemented using a stepped-impedance lowpass filter(LPF) and a composite quarter-wave short stubs where the LPF is functioning as attenuating the upper stopband and quarter-wave short stubs is functioning as attenuating the lower stopband. The measured results are as follows; the insertion loss is 0.65 dB at 30 GHz, the stopband characteristics are -10 dB and -16 dB at 10 GHz and 50 GHz, respectively, and the passband flatness is ${\pm}0.5$ dB at 20~40 GHz.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.4
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• pp.699-705
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• 2001

It is considered DPSK modulation and the channel is modeled as multipath Nakagami fading type which has been recently taken as a general model in the communication environments in this paper. Most paper assumed that Nakagami fading index(m) of each branch of Rake receiver was fixed the same value in recent years. However, Nakagami fading index(m) of each branch of Rake receiver takes several value through communication environments. In this case, the branch ,which takes a small Nakagami fading index(m), exclude. So we can improve performance. We are considered phase error and analyzed wideband DS/CDMA cellular system. When nakagami fading index(m) takes voluntary value, we analyze BER of wideband DS/CDMA cellular system. Finally, When the branch, which takes a small Nakagami fading index(m), exclude, we analyze BER of wideband DS/CDMA cellular system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.4
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• pp.494-500
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• 2020

This paper proposes a new distance estimation technique for indoor localization in ultra wideband (UWB) systems. The proposed technique is based on recurrent neural network (RNN), one of the deep learning methods. The RNN is known to be useful to deal with time series data, and since UWB signals can be seen as a time series data, RNN is employed in this paper. Specifically, the transmitted UWB signal passes through IEEE802.15.4a indoor channel model, and from the received signal, the RNN regressor is trained to estimate the distance from the transmitter to the receiver. To verify the performance of the trained RNN regressor, new received UWB signals are used and the conventional threshold based technique is also compared. For the performance measure, root mean square error (RMSE) is assessed. According to the computer simulation results, the proposed distance estimator is always much better than the conventional technique in all signal-to-noise ratios and distances between the transmitter and the receiver.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.5
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• pp.31-36
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• 2024

In this paper, we designed and manufactured an ultra-wide band X-band SAR transceiver to implement HRWS. The manufactured transceiver is designed to operate at a bandwidth of 1500MHz, which results in a distance resolution performance of approximately 26cm at 67degrees incidence angle. To improve IRF performance, which is a performance indicator of wideband SAR signals, pre-distortion was performed for nonlinear distortion. Through predistortion, the PSLR value could be improved -13.13dB and -9.47 ISLR. To verify the de-chirp performance, a wide chirp signal was applied to the receiver's input and local signal. As a results, the -13.5dB PSLR value was confirmed through direct mixing of the chirp signal at the receiver. Through the developed ultra-wideband SAR transceiver technology, it is possible to achieve distance resolution of several tens of centimeters, and it is confirmed that not only direct receiving of wideband chirp signal but also de-chirp signal receiving by mixing wide chirp signal.